I have been looking at various streming device and while the HD1000 has not got everything on my wish list I think and hope it fits the bill

Lets Start, what I was looking for was a device that will connect to my imac G4, streaming my ripped dvd collection, mp2/3/4 audion and video file and be wifi.
Well mp4 is out and wifi would not be fast enough so when I move into my new house soon I will have to get the cat 5 cable out.
I have read various different posts in the last few day that are of interest, the most interesting on being about a Linksys product that turn USB drives into NAS, the ability to have a drive connected and not have to have my computer on would be usefull, how easy is this or have I got the wrong end of the stick?
What is the limit on a compact flash card? as I have a nice 1GB that woukd be usefull to keep a movie and a few tunes on for easy playback.
Going back to mpeg 4 is this a hardware limitation or just a furure firmware uprade?
Using a mac I will be using mac the ripper to rip my dvd collection so I can archive the originals, do I have to convert them to anything else?
Thanks for your time and hopefully will be parting with my cash if the answers are good.
Cheers